As is known, numerous MEMS devices are available today. For example, the so-called MEMS reflectors are known, which include mobile elements formed by mirrors.
In general, a MEMS reflector is designed to receive an optical beam and to vary the direction of propagation thereof, via its own mirror. Typically, the direction of propagation of the optical beam is varied in a periodic or quasi-periodic way so as to carry out scanning of a portion of space with the reflected optical beam.
Further known are MEMS reflectors of a resonant type. In general, a resonant MEMS reflector comprises an actuation system that causes oscillation of the respective mirror in a substantially periodic way around a resting position, the oscillation period being as close as possible to the resonance frequency of the mirror in order to maximize the angular distance covered by the mirror during each oscillation, and thus maximize the size of the portion of space scanned.
In order to improve the resolution with which the optical beam carries out scanning, there is felt the need to provide MEMS reflectors with mirrors having diameters greater than the ones available today, and with resonance frequencies higher than or equal to the ones available today. For this reason, driving systems are required that are able to apply greater forces on the mirrors. In this connection, generally the actuation systems implemented in MEMS reflectors are of an electrostatic or electromagnetic type.
In order to increase the force applied on the mirror, there have been proposed actuation systems of a piezoelectric type, as described for example in U. Baran, “Resonant PZT MEMS Scanner for High-Resolution Displays”, Journal of Micro-electro-mechanical Systems, vol. 21, No. 6, pp. 1303-1310, 2012 (incorporated by reference). However, the solutions proposed are characterized by relatively large overall dimensions, and thus by high manufacturing costs.
There is a need to provide a MEMS device with piezoelectric actuation that will solve at least in part the drawbacks of the known art.